Types of Metals: A Complete Guide
- Written By: Gavin Leo
- Updated By: CoCo
- Published:
- Updated:
Before diving into specific metals, let’s start with the basic types. Metals fall into two main categories depending on their iron content: ferrous metals and non-ferrous metals. The word “ferrous” comes from the Latin word for iron.
Ferrous metals contain iron as their primary element. These type of metals have magnetic properties and can rust when exposed to water. Common examples of ferrous metals include carbon steel, cast iron, and wrought iron.
Non-ferrous metals do not contain iron. Compared to other metals, they are typically lighter. They likewise offer better corrosion resistance and do not have magnetic properties. The most common examples are copper alloys, aluminum, zinc, and precious metals like gold and silver.
In the periodic table of elements, the metallic elements are organized according to their chemical properties and atomic structure. Metals make up more than 75% of the chemical elements in the periodic table. This only shows how abundant metals are in nature and how important they are to development.
What is Metal?
Metal is a class of materials characterized by high electrical conductivity, thermal conductivity, malleability, ductility, and a lustrous appearance. Metals are typically solid at room temperature (except mercury) and form positive ions (cations) in chemical reactions.
Its characteristics enable it to be used in CNC processing, sheet metal fabrication, casting, welding and other processes. It can be made into various shaped profiles or parts, as well as various structural components.
There are over 100 different elements in the periodic table, but only a handful of them are considered to be metal.
Summary Table: Metals Types & Their Characteristics, Applications
| Types of Metal | Characteristics | Common Applications |
| Aluminum | Lightweight, soft, corrosion-resistant, high strength-to-weight ratio, conductive | Construction, machinery, tools, automotive |
| Carbon Steel | Strong, durable, recyclable, good plasticity, high toughness | Construction, machinery, tools, automotive |
| Tool Steel | High hardness, wear-resistant, maintains hardness at high temps | Cutting tools, dies, measuring instruments |
| High Carbon Steel | Very hard, brittle, high carbon content (0.60–0.95%) | Cutting tools, wear-resistant parts |
| Alloy Steel | Enhanced properties (strength, hardness, corrosion resistance) via alloying | Automotive, aerospace, industrial machinery |
| Stainless Steel | ≥12% chromium, corrosion-resistant, durable | Kitchenware, medical devices, architecture |
| Iron (Wrought) | Low carbon ( | Buildings, bridges, fences |
| Cast Iron | High carbon (>2%), hard, brittle, good casting | Engine blocks, pipes, cookware |
| Pig Iron | High carbon, brittle, unmalleable, raw material | Refined into steel/cast iron |
| Copper | Soft, conductive (heat/electricity), malleable | Electrical wiring, plumbing |
| Brass | Copper-zinc alloy, durable, low friction, golden color | Decorative items, valves, musical instruments |
| Bronze | Copper-tin alloy, harder than copper, corrosion-resistant | Statues, bearings, coins |
| Cobalt | Hard, brittle, magnetic, strengthens alloys | Magnets, aerospace alloys, batteries |
| Magnesium | Lightweight (1.74 g/cm³), strong, malleable | Aircraft parts, automotive components |
| Titanium | Strong, lightweight, corrosion-resistant, high melting point | Aerospace, medical implants |
| Nickel | Corrosion-resistant, heat-resistant, ductile | Electronics, batteries, alloys |
| Platinum | Dense, malleable, high melting point (1773°C) | Jewelry, catalytic converters |
| Lead | Soft, dense, low melting point, toxic | Batteries, radiation shielding |
| Chromium | Hard, brittle, adds strength/hardness to alloys | Stainless steel, plating, pigments |
| Gold | Malleable, non-corrosive, conductive | Jewelry, electronics, dentistry |
| Silver | Best electrical conductivity, malleable, tarnishes | Jewelry, electronics, mirrors |
Understanding Pure Metals and Metal Alloys, What's the Difference?
Fun fact: most of the metals we use every day are not refined metals. Most of them are metallic alloys, which are a combination of different metal elements to create better metallic properties.
The concept of metal alloys is similar to cooking. Pure flour works, but combining it with eggs, butter, and sugar can create something even better. The same principle applies to metals.
Pure iron, for example, is relatively soft and bends easily. It is not ideal for most industrial applications. However, if you add carbon to iron, you create steel. Steel is much stronger and more versatile. The amount of carbon determines the final product:
Low-carbon steel (less than 0.25% carbon) is soft, affordable, and easy to shape, making it perfect for construction and manufacturing
Medium carbon steel (0.25-0.55% carbon) balances strength and flexibility
High carbon steel (0.55-2.1% carbon) is harder and holds a sharp edge longer, making it ideal for cutting tools and knives
This process of combining elements to create alloys with better properties is what makes modern engineering possible.
What are the Properties of Metals?
Understanding different types of metal means knowing their unique properties:
Mechanical Properties
Tensile strength measures the pulling force of metals can withstand before breaking. High tensile strength is crucial for structural applications, such as buildings, cables, and bridges.
Hardness refers to resistance to scratching, denting, or deformation. Hardness is not synonymous with tensile strength. Harder metals maintain their shape under pressure but may be more brittle.
Ductility is the metal’s ability to be stretched without breaking. A high ductile material can be stretched into thin wires or bent into shapes without breaking. Common examples of high ductile materials are copper and gold.
Toughness combines strength with ductility. This refers to the ability to absorb energy without fracturing.
Electrical Properties
Thermal conductivity refers to the property of metals to transfer heat. Metals with high thermal conductivity allow heat to pass through them quickly. Metals like silver, copper, and aluminum are excellent heat conductors because their free electrons transfer thermal energy efficiently from one atom to another.
Melting point is the temperature at which metals change from solid to liquid. It reflects how strong the bonds between the metallic atoms. Metals with stronger metallic bonds require more energy to break those bonds.
The melting point varies dramatically between metals. Tungsten has the highest melting point of any metal at 3,422°C. Mercury is liquid at room temperature, with a melting point of −38.8°C.
Chemical Properties
Corrosion resistance refers to how well a metal withstands rust, oxidation, and chemical attack. When a metal corrodes, it reacts with oxygen or other substances to form rust. Corrosion weakens the metal and degrades its appearance.
Some metals naturally form protective layers. Aluminum creates aluminum oxide on its surface that shields it from external elements. Stainless steel’s chromium content forms a durable barrier on the surface.
Magnetic properties refer to the metal’s ability to attract or repel other metals under a magnetic field. This depends on the metal’s atomic structure. Ferromagnetic metals, like iron, nickel, cobalt, and their alloys, are strongly attracted to magnets. Non-ferrous metals like copper, aluminum, and brass are not magnetic.
Physical Appearance
Metallic luster is the shiny, reflective appearance of metals. The property results from the way the metal’s free electrons interact with light. When light hits the metal, the electrons absorb and re-emit light efficiently.
The color varies. Copper is reddish-brown, brass is golden, and aluminum is silver-white. These subtle differences help identify different metals. This also makes some metals desirable for decorative applications.
How to Choosing the Right Metal for Your Project
Metals have various properties distinct from each other. When selecting among different types of metal, consider:
Strength requirements: Does your application need high tensile strength, hardness, or impact resistance?
Weight constraints: Is a lightweight metal necessary, or is weight not a concern? Common examples of light metals include aluminum, magnesium, and titanium.
Environmental exposure: Will the metal face moisture, extreme temperatures, or chemicals? If the metal is always exposed to harsh conditions, you may want to have corrosion-resistant metals or metals with protective coatings.
Electrical needs: Are high electrical conductivity or specific electrical properties required?
Thermal considerations: Does thermal conductivity matter? Will it face high temperatures? You may choose metals with high thermal conduction if exposed to extreme conditions.
Budget: Pure metals and rare metallic alloys cost more than common materials like plain carbon steel.
Fabrication: Can it be cast, welded, machined, or formed into thin sheets as needed?
Magnetic requirements: Do you need magnetic metals or non-magnetic materials?
Appearance: Does metallic luster, color, or surface finish matter? Is it for decorative purposes?
FAQs
Q: What are the most common metal alloys?
A: The most common metallic alloys include:
- Steel (iron and carbon)
- Stainless steel (iron, carbon, and chromium)
- Brass (copper and zinc alloy)
- Bronze (copper and tin)
- Aluminum alloys (aluminum with copper, magnesium, or other elements) These alloys offer better mechanical properties than pure metals alone.
Q: What are the common aluminum?
A: The common aluminum alloys are 1050, 1100, 1145, 1235, 1350, and so on.
Q: What is the difference Stainless steel and Aluminum?
A: Stainless steel is an alloy of iron, chromium and carbon, while aluminum is a metal. Stainless steel is more resistant to corrosion than aluminum. Aluminum is lighter than stainless steel.
Q: What makes steel different from iron?
A: Steel is an iron-carbon alloy, sometimes with other metallic elements. The amount of carbon mixed into the iron determines the strength and durability of steel.
Q: Which metals are available for CNC machining?
A: The metals that are available for CNC machining are aluminum, brass, bronze, stainless steel, and other common metals.